<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="../css/reset.css">
    <style>
        .w {
            width: 1226px;
            margin: auto;
        }

        .nav {
            height: 100px;
            background-color: #eee;
            position: relative;
        }

        .nav h1 {
            width: 54px;
            height: 54px;
            margin: 23px;
            float: left;
            background-color: orange;
            border-radius: 20px;
        }

        .nav ul {
            float: left;
        }

        .nav li {
            float: left;
            line-height: 54px;
        }

        .nav li a {
            display: block;
            padding: 23px;
        }

        .hide {
            width: 100%;
            height: 300px;
            background-color: #ff0;
            position: absolute;
            left: 0;

            height: 0;
            overflow: hidden;
            transition: .3s;
        }

        .nav li:hover .hide {
            height: 300px;
        }
    </style>
</head>

<body>
    <div class="nav">
        <div class="w">
            <h1></h1>
            <ul>
                <li>
                    <a href="">首页</a>
                    <div class="hide"></div>
                </li>
                <li>
                    <a href="">首页</a>
                    <div class="hide"></div>
                </li>
                <li>
                    <a href="">首页</a>
                    <div class="hide"></div>
                </li>
                <li>
                    <a href="">首页</a>
                    <div class="hide"></div>
                </li>
                <li>
                    <a href="">首页</a>
                </li>
                <li>
                    <a href="">首页</a>
                </li>
            </ul>
        </div>
    </div>
</body>

</html>